1. Field of the Invention
The present invention relates to antifoams and/or deaeraters based on oil-in-water dispersions, which contain, in the hydrophobic oil phase, at least one compound effective as an antifoam and/or deaerater and, if required, further components.
2. Description of the Background
EP-A-0 149 812 discloses antifoams based on oil-in-water emulsions, which contain from 0.05 to 5% by weight of a high molecular weight, water-soluble homo or copolymer of acrylic acid, methacrylic acid, acrylamide or methacrylamide as a stabilizer. The oil phase of the emulsions contains, for example, as antifoam compounds, a C12-C26-alcohol, distillation residues which are obtained in the preparation of alcohols having a relatively large number of carbon atoms by oxosynthesis or by the Ziegler process and which may furthermore be alkoxylated. Further antifoam substances are, for example, fatty esters of C12-C22-carboxylic acids with a monohydric to trihydric C1- to C18-alcohol and/or hydrocarbons having a boiling point above 200° C. or fatty acids of 12 to 22 carbon atoms. The mean particle diameter of the oil phase of the oil-in-water emulsions is from 0.5 to 15 μm.
DE-A-30 01 387 discloses aqueous emulsifier-containing oil-in-water emulsions which contain aliphatic alcohols having a relatively high melting point and hydrocarbons which are liquid at room temperature. The oil phase of the oil-in-water emulsions can, if required, contain further components acting as antifoams, for example nonaromatic hydrocarbons, fatty acids or derivatives thereof having a relatively high melting point, for example fatty esters, bees' wax, carnauba wax, Japan wax and montan wax.
EP-A-0 531 713 discloses antifoams based on oil-in-water emulsions whose oil phase contains an alcohol of at least 12 carbon atoms, fatty esters of alcohols of at least 22 carbon atoms and C1- to C36-carboxylic acids, or fatty esters of C12- to C22-carboxylic acids with monohydric to trihydric C1- to C18-alcohols or a hydrocarbon having a boiling point above 200° C. or fatty acids of 12 to 22 carbon atoms in combination with polyglyceryl esters, which are obtainable by at least 20% esterification of the polyglycerol mixtures with at least one fatty acid of 12 to 36 carbon atoms. These oil-in-water emulsions, too, are stabilized with the aid of a water-soluble emulsifier.
EP-A-0 662 172 discloses antifoams based on oil-in-water emulsions, which are used as antifoams, for example in paper mills, and a re still sufficiently effective even at relatively high temperatures of the water circulations. Such antifoams contain, in the oil phase,    (a) fatty esters of C12- to C22-carboxylic acids with monohydric to trihydric C1- to C22-alcohol s,    (b) polyglyceryl esters which are obtainable by at least 20% esterification of polyglycerols which have at least 2 glycerol units with at least one C12- to C36-fatty acid and    (c) fatty esters of C12- to C22-carboxylic acids and polyalkylene glycols, the molar mass of the polyalkylene glycols being up to 5000 g/mol. The hydrophobic phase can, if required, contain further components, such as alcohols of at least 12 carbon atoms or hydrocarbons having a melting point above 200° C. These oil-in-water emulsions are likewise stabilized with the aid of an emulsifier.
EP-A-0 696 224 discloses aqueous antifoam dispersions whose dispersed phase contains fatty alcohols having melting points above 40° C. and ketones having melting points above 45° C. and, if required, natural or synthetic waxes having melting points above 50° C.
EP-A-0 732 134 discloses antifoams and/or deaeraters based on oil-in-water emulsions for aqueous media which have a tendency to foam formation, the oil phase of the emulsions containing    (a) at least one alcohol of at least 12 carbon atoms, distillation residues which are obtainable in the preparation of alcohols having a relatively large number of carbon atoms by oxosynthesis or by the Ziegler process or mixtures of said compounds and    (b) at least one ester of a sugar alcohol having at least 4 OH groups or at least 2 OH groups and at least one intramolecular ether bond and of a fatty acid of at least 20 carbon atoms in a molar ratio of 1 to at least 1, the free OH groups of this ether being completely or partially esterified, if required, with C12- to C18-carboxylic acids.
The hydrophobic phase can, if required, contain further antifoam compounds, such as fatty esters of alcohols of at least 22 carbon atoms and C1- to C36-carboxylic acids, polyethylene w axes, natural waxes, hydrocarbons having a boiling point above 200° C. or fatty acids of 12 to 22 carbon atoms.
The non-prior-published DE-A-19835968.3 discloses antifoams and/or deaeraters which are based on oil-in-water dispersions and contain, in the hydrophobic oil phase, at least one compound effective as an antifoam and/or deaerater and, if required, further components and which are stabilized with the aid of from 0.01 to 3% by weight, based on the oil phase, of a water-soluble, amphiphilic copolymer having acid groups or of a water-soluble salt thereof. DE-A-19641076 discloses antifoams which are used both as oil antifoams and in the form of an emulsion antifoam in the paper industry. The oil phase of the antifoams contains, as active components, reaction products which are obtainable, for example, by reacting mono- or diglycerides with dicarboxylic acids and/or their methyl and/or ethyl esters.
It was an object of the present invention to provide novel antifoams and/or deaeraters based on oil-in-water dispersions.